A data reading method, raid controller and storage device

Abstract

A data reading method, an RAID controller, and a storage device. The method comprises: receiving a read input / output (IO) request delivered by a host (201); determining, according to the size of the read IO request, an interval of an interval set to which the read IO request belongs (202); the interval set comprising at least two intervals and each interval in the interval set being corresponding to a target delay threshold; adjusting the target delay threshold of the interval in the interval set at the interval of a preset first period according to a preset threshold adjustment policy (203); monitoring a delay value returned by the read IO request (204); and when it is determined that the delay value of the read IO request exceeds the target delay threshold, performing a degraded read operation on the read IO request (205). By means of the method, the average delay of a system can be effectively reduced, and RAID performance of an SSD can be utilized to the greatest extent, thereby improving IO performance of the RAID.

Description

technical field [0001] The invention relates to the storage field, in particular to a data reading method, a RAID controller and a storage device. Background technique [0002] With the rapid development of solid state drive (Solid State Drives, SSD) technology, the storage capacity of the SSD is getting larger and the reading and writing speed is getting faster and faster, and its application range is getting wider and wider. However, as the erasing times of SSD particles increase, especially when the flash memory chip NAND Flash is about to reach the upper limit of its wear value, a small amount of input and output (InputOutput, IO) needs to go through multiple read retries or use SSD Only other processing measures in the SSD can read the correct data. At this time, the delay of reading IO will be much larger than that of normal reading IO. In addition, as the number of erasing and writing of particles increases, the overall performance of SSD will gradually deteriorate. I...

AI Technical Summary

Problems solved by technology

[0005] However, the existing method of keeping the delay value constant during operation does not take into account other influencing factors, such as changes in the IO delay distribution caused by changes in the ratio of read and write IOs and the size distribution of IOs. , this change usually leads to a large change in the delay value of IO. Therefore, whether it is a disk array composed of mechanical hard disks or a disk array composed of SSDs, a fixed delay threshold cannot well limit the timeout IO to reduce the overall The level of read IO delay; in addition, for a disk array composed of SSDs, since the delay value is fixed, in the case of a fixed delay value, for a slow IO, the delay value of slow IO completion is not It is not necessarily slower than the delay value of the slow IO downgraded read completion, so the effect of reducing the average delay of the system by downgrading the slow IO does not always exist; in addition, the 4KB random read rate of the SSD is very high, and the IO request Generally, they are also at the KB level. Therefore, in a disk array composed of SSDs, the degraded reading of some IOs will not have a significant impact on the performance of other SSDs in the disk array. Therefore, the method of fixing the delay threshold Does not work well in disk arrays composed of SSDs

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